using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Text;

using System.Windows.Forms;

 

namespace e

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }

 

        private void button1_Click(object sender, EventArgs e)

        {

            double ee = 1;

            int f = 1;

            for (int i = 1; i <= Int32.Parse(textBox1.Text); i++)

            {

                f = f * i;

                ee = ee + (double)1 / f;

            }

            textBox2.Text = ee.ToString();

        }

    }

}